Chapter 6. Configuring OVN-Kubernetes internal IP address subnets

Prerequisites

• Install the OpenShift CLI (oc).
• Log in to the cluster with a user with cluster-admin privileges.
• Ensure that the cluster uses the OVN-Kubernetes network plugin.

Procedure

• To change the OVN-Kubernetes join subnet, enter the following command:

  $ oc patch network.operator.openshift.io cluster --type='merge' \
    -p='{"spec":{"defaultNetwork":{"ovnKubernetesConfig":
      {"ipv4":{"internalJoinSubnet": "<join_subnet>"},
      "ipv6":{"internalJoinSubnet": "<join_subnet>"}}}}}'

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  where:

  <join_subnet>

  Specifies an IP address subnet for internal use by OVN-Kubernetes. The subnet must be larger than the number of nodes in the cluster and it must be large enough to accommodate one IP address per node in the cluster. This subnet cannot overlap with any other subnets used by OpenShift Container Platform or on the host itself. The default value for IPv4 is 100.64.0.0/16 and the default value for IPv6 is fd98::/64.

  Example output

  network.operator.openshift.io/cluster patched

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Verification

• To confirm that the configuration is active, enter the following command:

  $ oc get network.operator.openshift.io \
    -o jsonpath="{.items[0].spec.defaultNetwork}"

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  The command operation can take up to 30 minutes for this change to take effect.

  Example output

  {
    "ovnKubernetesConfig": {
      "ipv4": {
        "internalJoinSubnet": "100.64.1.0/16"
      },
    },
    "type": "OVNKubernetes"
  }

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Prerequisites

• Install the OpenShift CLI (oc).
• Log in to the cluster as a user with cluster-admin privileges.

Procedure

• Change your cluster’s masquerade subnet:

  • For dualstack clusters using IPv6, run the following command:

    $ oc patch networks.operator.openshift.io cluster --type=merge -p '{"spec":{"defaultNetwork":{"ovnKubernetesConfig":{"gatewayConfig":{"ipv4":{"internalMasqueradeSubnet": "<ipv4_masquerade_subnet>"},"ipv6":{"internalMasqueradeSubnet": "<ipv6_masquerade_subnet>"}}}}}}'

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    where:

    ipv4_masquerade_subnet

    Specifies an IP address to be used as the IPv4 masquerade subnet. This range cannot overlap with any other subnets used by OpenShift Container Platform or on the host itself. In versions of OpenShift Container Platform earlier than 4.17, the default value for IPv4 was 169.254.169.0/29, and clusters that were upgraded to version 4.17 maintain this value. For new clusters starting from version 4.17, the default value is 169.254.0.0/17.

    ipv6_masquerade_subnet

    Specifies an IP address to be used as the IPv6 masquerade subnet. This range cannot overlap with any other subnets used by OpenShift Container Platform or on the host itself. The default value for IPv6 is fd69::/125.

  • For clusters using IPv4, run the following command:

    $ oc patch networks.operator.openshift.io cluster --type=merge -p '{"spec":{"defaultNetwork":{"ovnKubernetesConfig":{"gatewayConfig":{"ipv4":{"internalMasqueradeSubnet": "<ipv4_masquerade_subnet>"}}}}}}'

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    where:

    ipv4_masquerade_subnet::Specifies an IP address to be used as the IPv4 masquerade subnet. This range cannot overlap with any other subnets used by OpenShift Container Platform or on the host itself. In versions of OpenShift Container Platform earlier than 4.17, the default value for IPv4 was 169.254.169.0/29, and clusters that were upgraded to version 4.17 maintain this value. For new clusters starting from version 4.17, the default value is 169.254.0.0/17.

Prerequisites

• Install the OpenShift CLI (oc).
• Log in to the cluster with a user with cluster-admin privileges.
• Ensure that the cluster uses the OVN-Kubernetes network plugin.

Procedure

• To change the OVN-Kubernetes transit subnet, enter the following command:

  $ oc patch network.operator.openshift.io cluster --type='merge' \
    -p='{"spec":{"defaultNetwork":{"ovnKubernetesConfig":
      {"ipv4":{"internalTransitSwitchSubnet": "<transit_subnet>"},
      "ipv6":{"internalTransitSwitchSubnet": "<transit_subnet>"}}}}}'

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  where:

  <transit_subnet>

  Specifies an IP address subnet for the distributed transit switch that enables east-west traffic. This subnet cannot overlap with any other subnets used by OVN-Kubernetes or on the host itself. The default value for IPv4 is 100.88.0.0/16 and the default value for IPv6 is fd97::/64.

  Example output

  network.operator.openshift.io/cluster patched

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Verification

• To confirm that the configuration is active, enter the following command:

  $ oc get network.operator.openshift.io \
    -o jsonpath="{.items[0].spec.defaultNetwork}"

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  It can take up to 30 minutes for this change to take effect.

  Example output

  {
    "ovnKubernetesConfig": {
      "ipv4": {
        "internalTransitSwitchSubnet": "100.88.1.0/16"
      },
    },
    "type": "OVNKubernetes"
  }

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